What was done to Sergei Magnitsky was appalling - that is not an excuse for a terrible piece of law. But that's what is being proposed as the Magnitsky Amendment. As Margaret Hodge (and it would be she pushing such a nonsense, wouldn't it?) explains:

Our amendment places a duty on ministers to ask the High Court to place a designation order on people who were involved in, or profited from, the worst human rights abuses. Once an individual is subject to a designation order, the enforcement authorities will have a duty to freeze their British assets.

Seems fair enough, freeze the assets of the evil ones. Except:

More than £100 billion is laundered through Britain each year but only £100 million — a fraction of the amount — is frozen. The Magnitsky amendment will close gaps in the law. Individuals and NGOs can also take matters into their own hands and apply for designation orders, sending a clear signal that inaction by the government and enforcement authorities is not acceptable.

Such as the right to family life, the right to freedom of religion, free elections, even religious education. Thus, for example, those who would abolish religious schools in the UK could have their assets frozen. Officials from countries which regard a Muslim embracing another faith as the crime of apostasy could have their assets frozen. All Cuban government officials could have their assets frozen as a result of the absence of free elections for 55 years which we admit would be fun to see.

And any Tom Dick or Harry can apply for such an order to be made.

No, this is not good law. If it does pass there would be a terrible temptation for us to start organising cases against those who do breach some of those rights. Cuba first perhaps. Closely followed by HMRC attempting to insist upon payment of disputed tax bills before a court has ruled upon the issue. But however much fun we might have with it it would still be bad law. Thus it really should not be passed into said law.

For this rather comes under the general rubric about power and the law. You never, ever, want to put into the law something that you don't want your enemy or rival using against you and yours. And we really would have fun using this.